The Irish Farmers' Association has accused Waterways Ireland and the ESB of not doing their job properly in containing floods from the River Shannon.
The IFA called for urgent action to tackle the problem.
However, Waterways Ireland said it continuously monitors water levels on the Shannon and takes immediate action when appropriate.
The IFA said water levels in Lough Derg and Lough Ree in particular are too high and the problem needs to be addressed immediately.
It said Waterways Ireland and the ESB need to act faster when it comes to flood warnings.
IFA Flooding Project Team Chairman Michael Silke said he visited Meelick, Co Galway, during 24 hours of non-stop rain on Thursday of last week.
He said he found that only one third of the gates, which were put in place to control water levels, were open.
He said no-one was being held responsible and that people in the area were suffering.
Waterways Ireland has rejected the claims.
A spokesperson said it monitors water levels on the Shannon on a daily basis and takes immediate action when appropriate and constantly monitors the Met Éireann forecasts.
With regard to the flooding last week, Waterways Ireland said it checked the water levels on the Shannon at 8pm last Wednesday night and the level was under summer levels.
Rain interrupts Cork Summer Show
Separately, heavy rain has forced the cancellation of the Cork Summer Show.
The organisers, Munster Agriculture Society had hoped that all events scheduled for today would take place on Sunday, however it will not go ahead due to and ongoing rainfall.
The show is one of the oldest agriculture festivals in Ireland.
Up to 25,000 people were expected to attend the event in Curraheen in Bishopstown.
